<link href="../global.css" rel="stylesheet" type="text/css" />
Here your link reference is a relative one - that means different locations viewed from different folders.
Or you write it absolutely, for example (assuming the css file is located there)
<link href="/assets/css/global.css" rel="stylesheet" type="text/css" />
But even better is to insert the line
<base href="[[++site_url]]" />
into all the templates and refer to the file leaving out the leading backslash:
href="assets/css/global.css"